The demand for degreasing formulations for a myriad of cleaning applications is well known. Target applications range from the light cleaning of printed electronic circuit boards to the cleaning of used automotive parts. Many formulations for these purposes contain varied levels of volatile solvents to efficiently degrease surfaces. Many heavy duty degreasing operations use heated solvent baths.
Recent concerns for environmental and toxicological effects of solvents and solvent baths have caused a full search for aqueous degreasing systems without solvent. Few surfactant based systems have been successful without at least a minor amount of solvent, for the dual purpose of cleaning and defoaming. Hence, industrial and institutional cleaning operations that require degreasing must reconcile their desire to be socially conscious with the need to remain effective.
The use of glycol ether solvents or cycloalkanes in cleaning compositions, in combination with anionic and/or nonionic surfactants, are known in the art. Examples of such systems may be found in Wittel et al., EP 376367; Kao Corporation, JP 3062896; Lyubarskay et al., SU 1300041; Bedo et al., SU T56873; and Dudesek et al., CS 220985.
Bobsein, et al, U.S. Pat. No. 4,663,082, teach a high pH water based industrial cleaning composition comprising a series of anionic surfactants, builders and alkalinity agents. In addition, the patentees teach the use of phosphate builders and chelating agents.
Henkel AG World Organization Patent No. 91/10718 discloses a composition requiring at least one anionic surfactant and at least one monocarboxylic acid.
European Patent No. 0392394B1 issued to the Nippon Paint Co. of Japan teaches a degreasing composition and a surfactant package comprising a nonionic surfactant of the polyoxyalkylene ether type with a phosphate polyethylene oxide adduct. This mix is combined with a necessary amount of alkali builder of varying types. However, the phosphate moiety is responsible for increasing the generation of foam. Finally, residual phosphorous is an environmental concern. The nominal amount of alkali builder also results in a caustic solution.
Further, European Patent No. 008441 B1 assigned to Albright & Wilson Limited teaches the use of a wide variety of nonionic surfactants or a phosphate ester with an alkanolamide and solvent U.S. Pat. No. 5,536,438, discloses a cleaning composition containing four nonionic surfactants (fatty alcohol ethoxylates) of different HLB values; U.S. Pat. No. 5,518,648 discloses a dishwashing composition comprising 2 nonionic surfactants of the alcohol alkoxylate type and a block copolymer of EO/PO; U.S. Pat. No. 5,382,376, discloses a detergent composition comprising: (a) EO/PO/EO block copolymer, (b) cosurfactants such as EO/PO/EO block copolymers with a hydrophobic moiety, (c) hydrophobic solvents such as alkylbenzenes; U.S. Pat. No. 5,049,376 discloses a detergent composition comprising surfactants selected from anionic, zwitterionic, cationic and nonionic; non phosphate builders, EO/PO block copolymers, and a polycarboxylate polymer.
Finally, U.S. Pat. No. 5,501,816 (US '816) discloses ternary surfactant blends comprising: alcohol alkoxylate with a fatty alcohol moiety, alkyl phenol alkoxylates and alkyl oxyethylate. US '816 also discloses that the addition of polycarboxylate polymers enhances the efficacy of the degreaser compositions.
Applicants have surprisingly discovered a diblend cleaning composition that provides safe and effective cleaning power. Further, the present invention does not require the use of polkycarboxylates to enhance cleaning efficacy.